"all but gone"

The key phrase or expression is "all but," which can be used with a very large number of adjectives, participles, nouns, pronouns and verbs. (Have I left anything out?) If you type your phrase into the search box on the top of the previous page, you'll get some useful examples (and one that is questionable).

Perhaps you'd like to augment the discussion there with the one in the Oxford English Dictionary. One definition there is:

Here's a definition from the Oxford English Dictionary.

"c. all but: everything short of. Hence, advb. Almost, very nearly, well nigh: see ALL A. 8b."